Re: [RESEND PATCH v4 03/15] x86/resctrl: Add data structures and definitions for PLZA configuration

Hi Reinette,

On 8/11/2026 6:51 PM, Reinette Chatre wrote:
> Hi Babu,
> 
> On 8/11/26 2:10 PM, Babu Moger wrote:
>> On 8/10/26 21:58, Reinette Chatre wrote:
>>> On 7/7/26 2:50 PM, Babu Moger wrote:
>>>> Privilege Level Zero Association (PLZA) allows the kernel to use a
>>>> different CLOSID (and optionally RMID) than user mode on entry to kernel
>>>> mode. The CLOSID/RMID association is programmed per CPU via
>>>
>>> CLOSID is also optional, no? I am not able to recall now why this is not made
>>> optional in this implementation though. Could you please remind me and add
>>> it to the changelog for next time?
>>
>>
>> Yes, CLOSID is optional as well. Since PLZA was primarily focused on
>> allocation, I hadn't considered that use case initially. However,
>> there may be scenarios where a user wants to monitor kernel activity
>> without affecting or changing the existing allocation configuration.
>> That would introduce an additional operating mode(See below).
> 
> ok.
> 
> I think doing so will simplify supporting the different modes across systems
> that may not support allocation or monitoring.

Ack.

>> INHERIT_CTRL_AND_MON:
>> Kernel work inherits the allocation and monitoring from the user space
>> task. On x86 this means that kernel work shares the same CLOSID and
>> RMID as the user space task. This matches today's resctrl behavior.
>>
>> GLOBAL_ASSIGN_CTRL_INHERIT_MON_PER_CPU:
>> Kernel work uses a globally assigned allocation while monitoring is
>> inherited from the user space task. On x86 this means a CLOSID is
>> assigned for kernel work and the RMID is inherited from the user space
>> task. Default scope is all online CPUs; a subset may be selected via
>> the resctrl group interface. A CTRL_MON group is bound to this mode.
>>
>> GLOBAL_ASSIGN_CTRL_ASSIGN_MON_PER_CPU:
>> Kernel work uses globally assigned allocation and monitoring. On x86
>> this means both CLOSID and RMID are assigned for kernel work. Default
>> scope is all online CPUs; a subset may be selected via the resctrl
>> group interface. A CTRL_MON or MON group is bound to this mode.
>>
>> GLOBAL_INHERIT_CTRL_ASSIGN_MON_PER_CPU:   <--- New mode
>> Kernel work inherits the allocation from user task and monitoring is
>> globally assigned for kernel work. On x86 this means that kernel
>> work shares the same CLOSID as user task and kernel work user
>> globally assigned RMID. A MON group is bound to this mode.
> 
> I provided comments about this text in following patch. Apart from that,
> I think a CTRL_MON or MON group could be assigned to this mode?
> 

Yes. It can be CTRL_MON or MON group.

thanks
Babu